Converter control method without AC voltage sensor during asymmetric network voltage
A technology of power grid voltage and control method, applied in the direction of multi-phase network asymmetry reduction, multi-phase network elimination/reduction of asymmetry, AC network circuit, etc., can solve problems such as integral saturation, initial value sensitivity, zero drift, etc., to achieve Fast dynamic response speed, good adaptability, and the effect of improving dynamic response speed
Active Publication Date: 2017-01-11
INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
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[0007] The purpose of the present invention is to overcome the possible problems of zero drift, integral saturation, steady-state error, sensitivity to initial value and complex algorithm in the existing inverter without AC voltage sensor control on the one hand; The AC filter inverter without AC voltage sensor control cannot adapt to the grid voltage asymmetry, and a three-phase grid-connected inverter without AC voltage sensor control method when the grid voltage is asymmetrical is proposed
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[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.
[0025] The present invention builds a variable-frequency orthogonal filter based on a second-order generalized integrator (SOGI), and then based on the orthogonal filter and introduces a phase-locked loop control to build a grid voltage observer suitable for asymmetric grid voltage conditions. The voltage observer combined with the positive and negative sequence separation method is applied to the controller of the three-phase grid-connected inverter to realize the AC voltage sensor-free control of the inverter.
[0026] The voltage observer can be derived according to the model of the three-phase grid-connected inverter, as shown in the following formula:
[0027] u α u β ...
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The invention discloses a converter control method without an AC voltage sensor during the asymmetric network voltage. The method comprises the steps: firstly building a quadrature filter for the no-difference following characteristics of an AC signal with the specific frequency through employing a second-order generalized integrator, and building a voltage observer of a three-phase grid-connected inverter under the condition of the asymmetric network voltage through employing the quadrature filter; firstly taking a measured power grid side current signal and an output bridge end reference signal of an inverter controller as the input of the voltage observer in a two-phase static coordinate system, and carrying out the observation of the network voltage; thirdly carrying out the positive and negative separation based on the output quantity of the quadrature filter, thereby enabling the positive and negative separation and the network voltage observation to be carried out synchronously; finally combining with the PR control of the three-phase grid-connected inverter in the two-phase static coordinate system and employing a negative compensation algorithm, thereby achieving the control of the inverter without the AC voltage sensor under the condition of the asymmetric network voltage.
Description
technical field [0001] The invention relates to a control method of a three-phase grid-connected inverter. Background technique [0002] The renewable energy grid-connected power generation system has developed rapidly in recent years. When it is connected to the end of the grid or the distribution network with a weak grid structure, there may be a small short-circuit capacity of the grid-connected point, poor stability of the grid, and serious problems in the grid. Problems such as voltage fluctuations, flicker, symmetrical or asymmetrical voltage drop faults, etc. The intermittence and randomness of renewable energy itself may further deteriorate the voltage stability of the connected power system, and in turn affect its own stable operation. In order to realize the grid-connected power and current control of renewable energy generation systems, the existing grid-connected converters or inverters generally use phase-locked loops to obtain grid voltage information, but thi...
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Login to View More IPC IPC(8): H02J3/38H02J3/26
CPCH02J3/26H02J3/38H02J2203/20Y02A30/60Y02E40/50
Inventor 胡书举龚文明王玲玲
Owner INST OF ELECTRICAL ENG CHINESE ACAD OF SCI